DCL

An elegant OOP with mixins + AOP for JavaScript.

getInherited()

This function determines a super method dynamically. It returns it as result, but unlike inherited() it doesn’t call it immediately. If there is no super method, a falsy value is returned.

While it is slower than the normal way to do supercalls with dcl (see the decorator dcl.superCall() for details), it doesn’t require to modify a method according to the double function pattern, and can be applied to undecorated methods, which makes it suitable for fast prototyping, and transitioning legacy code.

As soon as inherited.js is included, it mixes in getInherited() as a method to all newly created objects, so you don’t need to use the result of the module directly.

getInherited() works in strict mode.

Description

This is a companion method for inherited(). In fact, it is used in its implementation. Just like inherited(), it doesn’t require to decorate a method, and can be used to add a supercall to any arbitrary method, which makes it suitable for transitioning legacy code or fast prototyping:

getInherited()
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var B = dcl(A, {
  // The getInherited() way:
  calcPrice1: function(x){
    var sup = this.getInherited(B, "calcPrice1");
    if(sup){
        // Let's inflate price by 200%.
        // Asking for a real price in three different
        // yet equivalent ways:
      var realPrice1 = sup.apply(this, arguments);
      var realPrice2 = sup.apply(this, [x]);
      var realPrice3 = sup.call(this, x);
      // Now let's return it tripled:
      return realPrice1 + realPrice2 + realPrice3;
    }else{
      // There is no super method.
      return 0;
    }
  },

  // Compare it with dcl.superCall() example:
  calcPrice2: dcl.superCall(function(sup){
    // Let's inflate price by 200%.
    return function(x){
      if(sup){
          // Asking for a real price in three different
          // yet equivalent ways:
        var realPrice1 = sup.apply(this, arguments);
        var realPrice2 = sup.apply(this, [x]);
        var realPrice3 = sup.call(this, x);
        // Now let's return it tripled:
        return realPrice1 + realPrice2 + realPrice3;
      }else{
        // There is no super method.
        return 0;
      }
    };
  })
});

As you can see both getInherited() and dcl.superCall() look almost identical. The difference is:

For more details please take a look inherited().

FAQ

When should I use getInherited()?

There are three common scenarios when using getInherited() is beneficial:

  1. A method should make several calls to its super method. By using getInherited() and reusing its result, you save CPU ticks making the whole method faster. For even faster results consider using dcl.superCall().
  2. Your code behaves differently when there is no super method, and the default provided by inherited() just doesn’t work for you.
  3. While debugging, you don’t want to go inside inherited() (it is debugging-friendly, yet you may want to skip it completely while debugging). In this case you step over calls to getInherited() and debug your super methods directly.

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